In a typical electrostatic reproducing machine, a photoconductive insulating surface, often in the form of a moving belt, is uniformly charged and exposed to a light image from an original document. The light image causes the exposed or background areas to become discharged, and creates an electrostatic latent image on the surface corresponding to the image contained within the original document. Alternatively, a light beam such as a laser beam may be modulated and used to selectively discharge portions of the photoconductive surface to record the desired information thereon. The electrostatic latent image is made visible by developing the image with a developer powder, referred to in the art as toner, which may be subsequently transferred to a support surface such as paper to which it may be permanently affixed by the application of heat and/or pressure.
In order to provide a return path and/or monitoring capability for charges induced in the photoreceptor, brush contacts are generally used. Conventional photoreceptor ground brushes include, for example, a stainless steel spring type ground brush having a bundle of stainless steel wires or spring clips made from beryllium copper spring stock or stainless steel. In typical electrostatic reproducing machines airborne non-conductive contaminants can be plentiful. These non-conductive contaminants can cause contact integrity problems with the aforementioned wire brushes and clips to the extent that electrical contact may be lost entirely. In order to overcome some of the contamination problems, excessively high normal forces must be applied to maintain contact. This may even require that backup plates be used to assure pressure points. Such high forces can exacerbate failures because the high forces cause premature wear of the electroconductive ground strip on the photoreceptor. In this respect the metallic clips and brushes cause excessive drag forces on the photoreceptor by adding to the forces that must be overcome by the drive system components. Another type of failure associated with conventional ground brushes is deformation of the belt timing hole, which is typically part of the ground strip. The metal wires and clips easily cause the edges of the hole to degrade to the point where their detection by an optical sensor is impaired, thereby causing a system failure. The ends or sides of the stainless wire strands typically make contact with the carbonaceous ground strip on the photoreceptor. Both the stainless steel spring and the bundle of wires fail to provide a dense area of contact by virtue of their design and construction. For example, the density of the contact is limited by how many wires can be bundled. In addition, excessively high normal forces must often be applied to these wire contacts in order to maintain contact with a sliding surface.